Answer:
X^2+7x+4
Step-by-step explanation:

-8400/68 simplifies to to -2100/17, dolphins/year, so 2100 less dolphins every 17 years.
and we can just divide those to get the decimal amount of -123.53, which means, 123.53 less dolphins every year.
of course, there's no such a thing as 0.53 of a dolphin, so, we can say "about" 123 less dolphins per year.
ANSWER

EXPLANATION
We want to find the area of the shaded region.
We find the area of the smaller circle and subtract from the area of the larger circle.
Area of smaller circle is

Area of larger circle is

The area of the shaded region is:
